SAN FRANCISCO -- One day after the Kentucky Derby, the Giants likely will turn loose their most heralded thoroughbred.Right-hander Tim Lincecum, who has overmatched the Pacific Coast League with Triple-A Fresno, is the probable starter for Sunday's series finale against the Philadelphia Phillies at AT&T Park. Lincecum would replace Russ Ortiz, who went on the 15-day disabled list Thursday with right elbow neuritis.

Giants manager Bruce Bochy hedged only slightly when asked if Lincecum, 22, would make his Giants debut by filling Sunday's vacancy.

"We're expecting him to make that start," Bochy said. "But, obviously, we have a roster move to make if that's the case. So we're still thinking about it."

The Giants recalled infielder Kevin Frandsen from Fresno to take Ortiz's spot on the active roster.

Expectations have surrounded Lincecum since last June, when the Giants made him their No. 1 selection (10th overall) in the First-Year Player Draft and paid him a $2.025 million bonus. But the sense of anticipation soared even more once the season began and Lincecum dominated opponents through each of his five starts. He's 4-0 with an 0.29 ERA -- that's one earned run allowed in 31 innings -- while allowing 12 hits and walking 11. He has struck out 46, including 14 in his most recent start last Sunday against Colorado Springs.

As impressive as Lincecum looked in that game, Frandsen said that his previous effort might have demonstrated his competitive maturity more accurately. Facing Tucson on April 23, Lincecum surrendered his only run of the season in the second inning when he issued a leadoff walk, hit the next batter and flung a wild pitch before allowing a sacrifice fly. But Lincecum recovered to throw 6 1/3 no-hit innings, missing a chance to complete a no-hitter in the seven-inning contest (it was part of a doubleheader) because he exhausted his pitch count.

"That made me feel like he was ready for something bigger because he doesn't give in," Frandsen said, comparing Lincecum's stubbornness to Matt Cain's. "It's fun playing behind him. You want to see what's gonna happen."

Sunday's game happens to be scheduled for a national telecast on ESPN. But Bochy, who managed Lincecum in Spring Training, believes that the University of Washington product can cope with the hype.

"They're all TV games now," Bochy said. "If it is Timmy, that's not going to come into play with what he does. This is a tough kid. He handled himself well in the spring. If it turns out he makes that start, he'll be fine."

Having experienced a small measure of fuss as a native of nearby San Jose when he made his Giants debut last season, Frandsen can identify with what Lincecum will encounter. But, Frandsen said, "If he does what he normally does, which I honestly think he'll do, San Francisco is going to be in for a treat."

Of course... you'd expect Lincecum to show some type of struggle in his major league debut. 100 pitches through 4 1/2 innings. Had 5 nice strikeouts. They lost, Tim struggled, but what rookie doesn't? All I know is Lincecum's future is very bright.